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Yuchen Wang

Bio: Yuchen Wang is an academic researcher from University of Tokyo. The author has contributed to research in topics: Geology & Seismology. The author has an hindex of 8, co-authored 17 publications receiving 165 citations. Previous affiliations of Yuchen Wang include Peking University & Japan Agency for Marine-Earth Science and Technology.

Papers
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Journal ArticleDOI
TL;DR: In this paper, a newly compiled EOF-EEMD analysis visualization package was used to evaluate the spatiotemporal variability of ground-level NO2, PM 2.5, and their associations with meteorological processes over Eastern China in fall-winter 2013.
Abstract: . Eastern China (27–41 ∘ N, 110–123 ∘ E) is heavily polluted by nitrogen dioxide ( NO2 ), particulate matter with aerodynamic diameter below 2.5 µ m (PM 2.5 ), and other air pollutants. These pollutants vary on a variety of temporal and spatial scales, with many temporal scales that are nonperiodic and nonstationary, challenging proper quantitative characterization and visualization. This study uses a newly compiled EOF–EEMD analysis visualization package to evaluate the spatiotemporal variability of ground-level NO2 , PM 2.5 , and their associations with meteorological processes over Eastern China in fall–winter 2013. Applying the package to observed hourly pollutant data reveals a primary spatial pattern representing Eastern China synchronous variation in time, which is dominated by diurnal variability with a much weaker day-to-day signal. A secondary spatial mode, representing north–south opposing changes in time with no constant period, is characterized by wind-related dilution or a buildup of pollutants from one day to another. We further evaluate simulations of nested GEOS-Chem v9-02 and WRF/CMAQ v5.0.1 in capturing the spatiotemporal variability of pollutants. GEOS-Chem underestimates NO2 by about 17 µ g m −3 and PM 2.5 by 35 µ g m −3 on average over fall–winter 2013. It reproduces the diurnal variability for both pollutants. For the day-to-day variation, GEOS-Chem reproduces the observed north–south contrasting mode for both pollutants but not the Eastern China synchronous mode (especially for NO2 ). The model errors are due to a first model layer too thick (about 130 m) to capture the near-surface vertical gradient, deficiencies in the nighttime nitrogen chemistry in the first layer, and missing secondary organic aerosols and anthropogenic dust. CMAQ overestimates the diurnal cycle of pollutants due to too-weak boundary layer mixing, especially in the nighttime, and overestimates NO2 by about 30 µ g m −3 and PM 2.5 by 60 µ g m −3 . For the day-to-day variability, CMAQ reproduces the observed Eastern China synchronous mode but not the north–south opposing mode of NO2 . Both models capture the day-to-day variability of PM 2.5 better than that of NO2 . These results shed light on model improvement. The EOF–EEMD package is freely available for noncommercial uses.

44 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a new tsunami data assimilation approach based on Green's functions to reduce the computation time for tsunami early warning, which does not require the calculation of the tsunami wavefield for the whole region during the assimilation process.
Abstract: We propose a new tsunami data assimilation approach based on Green's functions to reduce the computation time for tsunami early warning. Green's Function-based Tsunami Data Assimilation (GFTDA) forecasts the waveforms at points of interest (PoIs) by superposition of Green's functions between observation stations and PoIs. Unlike the previous assimilation approach, GFTDA does not require the calculation of the tsunami wavefield for the whole region during the assimilation process, because the Green's functions have been calculated in advance. The forecasted waveforms can be calculated by a simple matrix manipulation. The application to the tsunami waveforms recorded by the bottom pressure gauges of the Cascadia Initiative from the 2012 Haida Gwaii earthquake reveals that GFTDA achieves the same accuracy as the previous assimilation approach while reducing the time required to issue a valid tsunami warning.

34 citations

Journal ArticleDOI
TL;DR: In this paper, a deployment of Offshore Bottom Pressure Gauge (OPG) is proposed for the Eastern Mediterranean Basin (EMB) under the threat of tsunami events triggered by various causes including earthquakes and landslides.
Abstract: The Eastern Mediterranean Basin (EMB) is under the threat of tsunami events triggered by various causes including earthquakes and landslides. We propose a deployment of Offshore Bottom Pressure Gau...

25 citations

Journal ArticleDOI
TL;DR: In this article, the authors used the two-layer model and nonlinear shallow equation model to study the triggering mechanism of the tsunami event and found that the most hazardous area is located at the south of the Sunda Strait (Pandeglang), which suffered the most casualties.
Abstract: The eruption and collapse of the Anak Krakatau volcano generated tsunamis in the Sunda Strait on December 22, 2018, leading to damage and casualties. In this paper, we use the two-layer model and nonlinear shallow equation model to study the triggering mechanism of the tsunami event. We first simulate the tsunami generated by volcano eruption and landslide, respectively. The tsunami source is analyzed by comparing with gauge measurements. It indicates that the volume of partial collapse for the landslide is 0.2–0.3 km3. The comparison between the numerical results of landslide and tide gauge measurements presents well-fitted results, especially for the leading tsunami waves and arrival time. Computed maximum tsunami amplitude distribution points out that the most hazardous area is located at the south of the Sunda Strait (Pandeglang), which suffered the most casualties.

23 citations


Cited by
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01 Jan 2016
TL;DR: The journal of the Society of Geomagnetism and Earth, Planetary and Space Sciences, The Seismological Society of Japan, The Volcanological Society, The Geodetic Society, and The Japanese Society for Planetary Sciences as mentioned in this paper.
Abstract: ▶ Gathers original articles on topics in earth and planetary sciences ▶ Coverage includes geomagnetism, aeronomy, space science, seismology, volcanology, geodesy and planetary science ▶ Official journal of the Society of Geomagnetism and Earth, Planetary and Space Sciences, The Seismological Society of Japan, The Volcanological Society of Japan, The Geodetic Society of Japan, and The Japanese Society for Planetary Sciences

477 citations

26 Oct 2009
TL;DR: In this paper, the abundance and size distributions of HULIS in ambient aerosols were measured in a rural location in South China at a time with a visible presence of crop residue burning.
Abstract: Abstract HUmic-LIke Substances (HULIS) comprise a significant fraction of the water-soluble organic aerosol mass and influence the water uptake properties of aerosols in the atmosphere. In this work, the abundance and size distributions of HULIS in ambient aerosols were measured in a rural location in South China at a time with a visible presence of crop residue burning. PM 2.5 samples of fresh smoke from burning rice straw and sugar cane leaves were also collected and analyzed for HULIS and major aerosol constituents. HULIS were abundant in both ambient samples and in fresh biomass burning emissions, accounting for ∼60% of the water-soluble organic carbon in the ambient aerosols and ∼30% in the fresh biomass burning aerosols. In the particles in the range of 0.32–1.8 μm, the abundance of HULIS was 40–90% of the combined abundance of sulfate and ammonium, suggesting that HULIS should be considered when quantifying the role of sulfate aerosols serving as cloud condensation nuclei. The size distribution of HULIS was characterized by a dominant droplet mode with a mass median aerodynamic diameter (MMAD) in the range of 0.63–0.87 μm, accounting for 81% of the total HULIS mass, a minor condensation mode (12%, MMAD: 0.23–0.28 μm) and a coarse mode (7%, MMAD: 4.0–5.7 μm). The small amount of HULIS in the coarse mode indicated that soil-derived HULIS was a very minor source. On the basis of the size distribution characteristics, HULIS were postulated to have multiple sources, including secondary formation in cloud droplets, secondary formation through heterogeneous reactions or aerosol-phase reactions, and primary emissions from biomass burning.

121 citations

Journal ArticleDOI
TL;DR: The FRD PM2.5 emissions inventory in a major inland city in China in 2017 was constructed at high-resolution, the spatiotemporal characteristics of the FRD emissions in different urban function zones were investigated, and their health impacts were quantified.
Abstract: Fugitive road dust (FRD) particles emitted by traffic-generated turbulence are an important contributor to urban ambient fine particulate matter (PM2.5). Especially in urban areas of developing countries, FRD PM2.5 emissions are a serious environmental threat to air quality and public health. FRD PM2.5 emissions have been neglected or substantially underestimated in previous study, resulting in the underestimation of modeling PM concentrations and estimating their health impacts. This study constructed the FRD PM2.5 emissions inventory in a major inland city in China (Lanzhou) in 2017 at high-resolution (500 × 500 m2), investigated the spatiotemporal characteristics of the FRD emissions in different urban function zones, and quantified their health impacts. The FRD PM2.5 emission was approximately 1141 ± 71 kg d-1, accounting for 24.6% of total PM2.5 emission in urban Lanzhou. Spatially, high emissions exceeding 3 × 104 μg m-2 d-1 occurred over areas with smaller particle sizes, larger traffic intensities, and more frequent construction activities. The estimated premature mortality burden induced by FRD PM2.5 exposure was 234.5 deaths in Lanzhou in 2017. Reducing FRD emissions are an important step forward to protect public health in many developing urban regions.

79 citations

Journal Article
TL;DR: In this article, the onset of heterogeneous ice nucleation was observed as a function of particle temperature (Tp), relative humidity (RH), nucleation mode, and particle chemical composition which is influenced by photochemical atmospheric aging.
Abstract: This study reports on heterogeneous ice nucleation activity of predominantly organic (or coated with organic material) anthropogenic particles sampled within and around the polluted environment of Mexico City. The onset of heterogeneous ice nucleation was observed as a function of particle temperature (Tp), relative humidity (RH), nucleation mode, and particle chemical composition which is influenced by photochemical atmospheric aging. Particle analyses included computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). In contrast to most laboratory studies employing proxies of organic aerosol, we show that anthropogenic organic particles collected in Mexico City can potentially induce ice nucleation at experimental conditions relevant to cirrus formation. The results suggest a new precedent for the potential impact of organic particles on ice cloud formation and climate.

59 citations

Journal ArticleDOI
TL;DR: It is reported that maternal and neonatal exposure to particulate matter increases the risk of neonatal jaundice based on the study of 25,782 newborns born in China between 2014 and 2017 and positive relationship between maternal exposure and newborn bilirubin level is quantitated.
Abstract: Clinical experience suggests increased incidences of neonatal jaundice when air quality worsens, yet no studies have quantified this relationship. Here we reports investigations in 25,782 newborns showing an increase in newborn’s bilirubin levels, the indicator of neonatal jaundice risk, by 0.076 (95% CI: 0.027–0.125), 0.029 (0.014–0.044) and 0.009 (95% CI: 0.002–0.016) mg/dL per μg/m3 for PM2.5 exposure in the concentration ranges of 10–35, 35–75 and 75–200 μg/m3, respectively. The response is 0.094 (0.077–0.111) and 0.161 (0.07–0.252) mg/dL per μg/m3 for SO2 exposure at 10–15 and above 15 μg/m3, respectively, and 0.351 (0.314–0.388) mg/dL per mg/m3 for CO exposure. Bilirubin levels increase linearly with exposure time between 0 and 48 h. Positive relationship between maternal exposure and newborn bilirubin level is also quantitated. The jaundice−pollution relationship is not affected by top-of-atmosphere incident solar irradiance and atmospheric visibility. Improving air quality may therefore be key to lowering the neonatal jaundice risk. Air pollution has become a major health risk in China. Here Zhang et al. report that maternal and neonatal exposure to particulate matter increases the risk of neonatal jaundice based on the study of 25,782 newborns born in China between 2014 and 2017.

56 citations